Wednesday, August 28, 2013

Species in last 3 months' papers in Ecology Letters.
"Multiple species" tended to be meta-analyses.

Browse the abstracts of a high profile ecological journal (for example, Ecology Letters, right) and one pattern you’ll notice is that high impact, hypothesis-driven ecology usually involves a small pool of focal species. Plants, for example, dominate any discussion of community ecology and have since Clements’ and Gleason’s arguments. It is not that hard to see why – plants don’t move, for one, live in speciose groups, and often complete a full lifecycle in a matter of months. They are also the lowest trophic level and so pesky multiple trophic level interactions can be omitted.

Other groups of species also show up frequently. Insects are popular for some studies of herbivory (again, it is easy to estimate damage to species that can’t move), mutualisms, and predation. Butterflies and birds, being pretty and easy to count, make a nice model for species populations and climate change studies. And while it is easy to sound critical of this kind of system-based myopia, it exists for perfectly good reasons. Immobile plants, after all, are a major source of experimental knowledge upon which much of modern ecology relies. They are easy to work with and manipulate, and their responses are relatively easy to measure (phenology, fitness, biomass, herbivory). Further, once an experimental system is established, using that system becomes increasingly attractive. You have a growing literature to base decisions on, to put your results into context, and against which to prove the novelty or importance of your work. In contrast, if you do your work on the rare bunny-toed sloth-monkey, the novelty of the system may overwhelm the generality of the work. And so the short-term limitation is that established systems allow immediate in-depth studies, while novel systems, though necessary to broaden ecological knowledge, may (initially) relatively be shallow in their returns.

Establishing a new system may be a time-consuming activity with the possibility of failure. But these under-utilized species have something new to tell ecology. This is not to say that the popular systems of species have nothing to tell us anymore – not at all, given all the complexities of ecological dynamics – but they bias the story. The ecological processes at play are not likely much different between novel systems and traditional ones. But the same processes interact in different ways and differ in importance across systems, and so we may have unrealistic expectations about the importance of, say, competition, if we only focus on 1 or 2 systems. To follow Vellend’s (2011) framework, the processes of selection, drift, speciation, and dispersal are part of any ecological system. What differs is their importance, and their importance differs for reasons related to the ecological context and evolutionary history a species experiences. This is the reason that comparing Mark McPeek’s work on neutrality in damselflies with Jonathan Losos’ findings about adaptive radiation in anoles is so interesting. No one questions that adaptive radiations may drive one set of species and neutrality another, the real question is what about their contexts produces to this result. Unfortunately, if our current set of focal species is small, we are limited in our ability to make such informative comparisons.

Many of the limitations on species have been methodological: popular systems tend to involve amenable species. Other species may be very small, very mobile, very difficult to identify, or highly specialized in their habitats. This creates difficulties. But when we overcome them, the results are often revolutionary. For example, consider the current burst of interest in belowground interactions, once their incredible importance to plant community interactions became clear (e.g. Klironomos 2002, Nature). Further, techniques are continually improving in ways which make new systems tenable.

So we should continue to focus on a few well-understood systems, attempting to perfect our understanding and predictive abilities. There is much value in understanding a system as completely as possible. But on the other hand, we can limit ourselves by focusing too much. It seems like one of the big areas for growth in modern ecology is simply to expand into novel ecological systems.

(**It's probably too general and a bit unfair to refer to all plants and all insects as though they are monolithic groups, since they are each large and varied (which is part of the reason they've been useful thus far). And some of their great representation may in fact relate to the number of species available to study. But I do think the general point about the problem of focusing too much holds.**)

For example, excitement for reviewing is proportional to the number of reviews you have done

When you are first asked, reviewing feels like a great honour. It is one of the first signs that some group larger than your lab or department recognizes your existence. You will spend an unreasonable amount of time perfecting your review.

This plot would not survive peer review.

The novelty will wear off, and your enthusiasm upon receiving a review request will decline, usually in relation to your increasing workload.

Sadly, the urgent need to complete a review may also wane. You will probably submit the first review early, but after that…

Despite declines in enthusiasm, review quality usually increases with the number of reviews you have done. Practice and experience make a difference. It is also a confidence boost to see your suggestions actually instituted and valued by the authors or editors.

Manuscripts fall broadly into only a few categories. They might be deeply flawed and unpublishable, and therefore easy to review; or they might be uniformly excellent and therefore easy to review. But these are the least common types you will experience. Most manuscripts have both strengths and weaknesses and fall somewhere on the spectrum between “accept” and “reject”. These are the papers that take the most time, since you must weigh the flaws against the strengths, agonize over what changes to suggest, what suggestions might get them around the biggest issues, and what recommendation to give the editor. It’s also easy to fall into Monday morning quarterbacking and make impractical suggestions - why didn’t you design your experiment like this? Why didn’t you measure that? While these points might be reasonable and relevant, but it is important to be clear as to what is within the scope of a revision and what is a bigger picture problem.

Reviewing is of course an important service to ecology. It can also makes a number of subtle contributions to your own professional development. Once the novelty of someone caring about your opinion has worn off, the best part of reviewing may be things you don’t expect.

For example, one of the best parts of reviewing a paper in the same area as your research is seeing what literature the authors cite and how they cite them– some real gems you've missed can show up.

Reviewing a paper that falls so exactly in your body of knowledge that you feel completely qualified is a great feeling. It’s nice to be reminded that you have (mostly) mastered a topic you care about.

When you are asked to review a paper that combines some topic or method you are well-versed in with ideas or systems or methodologies you are not familiar with, it can be truly eye opening. The funnest papers to review are the ones where you think “I never thought of that!”.

Reviewing can give you the clarity to recognize the weaknesses in your own work.

Thursday, August 22, 2013

I'm back in Toronto now, and here are some quotes from talks that have really stuck with me. INTECOL was a great meeting, it was very interesting to hear about all the research from around the world. I hope all the attendees had a great time.

Erika Edwards: “carbon economy is part of the whole
organism, not single traits.”

Joel Cohen: “Mathematics is like sex, you can talk about it
but you shouldn't do it in public.”

Enrique Chaneton, Describing what happen during a study
looking at the effects of grazing on ecosystem decomposition rates: “A volcano
erupted during the study and sometimes shit happens, ….. the volcano killed
many of the cattle.”

Carsten Meyer, Talking about global data availability in
large databases: “Countries that under report are large emerging economies
(china, India, Brazil, Russia) which could finance these efforts but for some
reason do not.”

Ove Hoegh-Guldberg, ‘To get change we need to reach more
than the brain, but the human heart”

This year's conference has a strong focus on infectious disease which included today's symposium Community ecology for infectious diseases organized by Joanne Lello.

Throughout the symposium a great deal of interesting questions related to host-parasite interactions being addressed with a diverse set of methods ranging from the mathematical biology of Andy Dobson, to the experimental C. elegans / pathogenic bacteria systems of Olivier Restif and Gregg Hurst, the wild rodent systems of Heike Lutermann, Andy Fenton, and Owen Petchey, and the next generation molecular techniques employed by Serge Morand.

However, it was Robert Poulin the keynote speaker who set the theme of the symposium to which many of the speakers kept returning: What are the future directions of parasite community ecology? Dr. Poulin began the session with an overview of the recent trends in parasite ecology over the last few decades and Lawton's view that community ecology is a mess (Oikos 1999 – 84: 177-192). The initial research done on host-parasite interactions was centred within the one host – one parasite framework, often dealing solely with the effect of the parasite on its host. This was then expanded to the one host – multi-parasite level, often investigating drivers of parasite species richness among hosts via comparative analyses and occasionally extending to parasite-parasite interactions though the use of null models. Although the data were available beforehand, only recently has the field moved into the domain of multi-host – multi-parasite interactions, now focusing on questions of infection dilution, meta-analyses of parasite richness, and describing the networks of interactions within these communities.

Looking ahead into the future of this discipline, Poulin suggested that researchers should expand beyond simple topological networks of associations to include the strength of interactions, potentially via energy flow, and the use of network analyses on smaller scales using individual hosts. Serge Morand also highlighted the need to develop and incorporate parasite phylogenies into these multi-host - multi-parasite communities. His talk highlighted recent advances in next generation sqeuenceing and how these techniques can be applied to parasite communities. One obvious advantage is that through molecular phylogenetics researchers will be able to define and quantify a higher degree of parasite diversity, but additionally molecular markers can be used to uncover unexpected host diversity or identify species that may be difficult to distinguish through traditional taxonomic keys. Morand continued to press the application of new techniques in immunogenetics and the integration of methods in molecular epidemiology with the theory of transmission and community ecology.

Finally Andy Dobson posited that in addition to pressing forward with our research into infectious disease, it is imperative that contemporary researchers revist the “best hits” of the past and address important issues that have fallen to the wayside. Primarily Dobson pointed out that mathematically, aggregation and virulence of parasites have been shown as important factors for determining parasite co-existence. However, the concept of aggregation is often left out of contemporary discussions although it will be important to determine natural forms of the aggregation distribution and also to attempt to make the link between immunity and aggregation of parasites in a multi-host – multi-parasite community.

Whether incorporating novel molecular and statistical techniques, exploring previously unstudied model systems, or revisiting the context of contemporary research, it is clear that community ecology and infectious disease has a promising future and that it has progressed greatly from the mess Lawton made it out to be in 1999.

Tuesday, August 20, 2013

Today I had a number of journal related obligations (for the Journal of Applied Ecology -which is celebrating its 50th anniversary here at the conference) and I had time to attend just a few talks. I saw some great talks -especially by Tad Fukami on evolutionary priority effects, but I decided to only post my (inadequate) notes about two of the plenary talks today. They were great talks, and both of them really expanded my perception of human-caused effects on natural systems, in very different types of habitats.

Ove Hoegh-Guldberg. Corals reefs and global climate change.
Coral reefs occupy less that one percent of ocean area but one in four fish caught
come from reefs, supporting 400 million people. In the Caribbean coral cover
has drastically declined from 80 percent cover to about 10 percent. This has
happened elsewhere too, Asia and Australia. In Australia, where coral reefs are
well protected and financed, they are still declining. Human development,
pollution from agriculture and over harvesting are the common local causes, but
global warming and ocean acidification are major global changes. Marine systems
are greatly warming, more than land, but very few studies in marine systems.
Increases in sea temperature can result in mass coral bleaching and death of
corals. Major bleaching events over the past two decades, killing significant
proportions of coral. Even though temperature is the best predictor of
bleaching, mortality is more variable and other factors may help corals
recovery, and these other factors are what managers can influence. In the
coming decades, warming temperatures will mean common widespread bleaching
events, with some areas becoming too warm for corals. Based on large mesocosms
that track local ocean temperature and co2 concentrations. With warming, the
mesocosm reefs change into algal dominated systems, with fewer other types of
species (e.g., sea cucumbers). Two scenarios to deal with climate change
-mitigate or adapt. We need to mitigate within twenty years, reduce co2
emissions. To get change we need reach more than the brain, but the human
heart. Partnered with Google to have street view for reefs (this is completely awesome -check it out here). This initiative is
both science (mapping reefs) and important outreach, letting people experience
diving. One billion people have visited with almost two million people 'dived'
in the first week.

Nancy Grimm. Water systems in urban habitats. Populations
around the world are moving to cities, and projections have over 650 cities
with over a million people by 2025. Creates multiple stressors in urban
ecosystems, and there is a new need to build knowledge capacity. Large
proportions of people already live in urban areas with limited water supply,
quality and delivery capacity. Eighty percent of the population lives in areas
under threat of water scarcity, but some people have access to technological
solutions that minimize this (e.g., arid USA). For others, ecological knowledge
may help reduce this threat. Areas around the world are experiencing more heavy
rainfall and flooding. The way municipalities deal with storm water is building
hard channels and surfaces, but building ecological systems can better handle
water and pollution. In the arid southwest, there are opportunities to retain
storm water in semi-natural systems. Provides ecosystem services and denitrification.

Sorry for the brevity of the talk summaries -I'm working on a very full schedule!

It is clear to me that INTECOL is the premiere ecological
meeting. There are delegates from countries all over the world from 67
countries , with especially strong European contingents. The next INTECOL
meeting will be in Beijing in 2017. This is a special INTECOL as this is the
100th anniversary of the British Ecological Society. The opening talk by Sandra
Diaz was held in an immense auditorium at the ExCeL centre, with a couple of
thousand in attendance.

Morning plenary:

Sandra Diaz: functional traits are at the core for
understanding changes in biodiversity and how species contribute to ecosystem
function. Theophrastus, Greek philosophers, created first functional groups.
Looks at key traits for tens of thousands of species, only possible through TRY
data base. Most variation explained by size ( height, seeds, etc.), second was
leaf economy ( leaf N, Leaf area, etc). These traits define plant functional
design. Densities low on the fringes of this trait space -physical challenges,
and many of these species use human help for success (crops and weeds). Two
dense areas in the trait space -big slow growing trees, and small species.
Effect and response traits are important for linking environmental change to
ecosystem services. These traits can be linked or decoupled, and could change
management options.

Linking trait dispersion and values to ecosystem function is
a new area, and so few studies. We just don't know enough to understand how
functional diversity links to environmental change and ecosystem services.

Sandra Diaz giving her plenary lecture

Tree of life in ecosystems symposium:

Lisa Donovan: how selective pressures influence evolution of
biogeochemical cycling. Traits appear evolutionary labile, and reported on a
common garden experiment to find genetic differences controlling traits.
Nitrogen has phylogenetic signal but few differences between close relatives.
Major differentiation within species and especially for different agricultural
lines.

Erika Edwards: Need to move down to small scale to truly
understand the evolution of traits that affect ecosystem function. She looks at
the genus Viburnum. Need to think about whole organism traits. E.g., branching
and growth pattern. This originates from tropics and reinvaded temperate
regions repeatedly, and a mix of different and similar strategies emerged.
growth patterns highly conserved, but leaf spectrum traits were not. Flowering
time seems linked to carbon economy traits.

Amy Zanne: Evolution and biogeography of leaf and stem
traits. Angiosperms originated in the tropics and understory woody species and
spread everywhere and all types of morphologies. Most species are woody and not
exposed to freezing, and lineages move back and forth in climate species but
less so with growth form. lineages shift growth form first, followed by climate
changes.

Cornwell. Evolution of decomposition. Differences in
decomposition rates among different phylogenetic lineages. Did plant life go
from fast cycling world to slow one during evolution. Experiment in common
garden for decomposition rates. basal angiosperms (magnolias) has lower
decomposition than eudicots, which has fast decomposition rates.

Afternoon plenary:

Joel Cohen. Taylor's law after half a century. Taylor's law
has been verified but we don't understand it. Taylor's law states that the
variance of a population is positively related to the mean population size.
Further mean population size is correlated with body size. He showed that tree
data supports a body size-variance relationship. Does it apply to food webs?
Data from aquatic systems show this pattern across species. Why do we care about
Taylor's law? Used for understanding fluctuations in epidemiology, conservation
of endangered species and management of forestry resources. Can see the same
variance-mean relationships in nonbiological data -computer data packets,
weather data and stock market trades. No underlaying theory to explains these.
Previous attempts, such as affects of competition, do not seem to affect
pattern.

Biodiversity & Ecosystem function session:

Enrique Chaneton. Movement of large herbivores around the
world, introduction of cattle versus reintroducing native extirpated
herbivores. Little is know how these large herbivores influence forests.
Multiple pathways of effect from changing plant composition and waste excretion,
affects decomposition. Within an Argentinean park, sites on lake islands do not
have introduced herbivores and compared to nearby mainland sites. Herbivores
reduce vegetation cover by sixty percent. Trees and shrubs were particularly
affected. Distinct composition shifts. Litter layer was substantially
different. In dry sites, higher decomposition in ungrazed sites. Volcanic
eruption during research 'sometimes shit happens' killed many of the cattle.

Carsten Meyer. Examined the completeness of species point
data inventories. Looked at GBIF records and compare to known distribution maps.
GBIF records are highly biased to North America, Europe and Australia. Species
rich areas are almost absent from GBIF records. Not adequate for research or
conservation. Funding, accessibility and human safety all at play for biases.
These factors seem to differ among taxonomy, interestingly. Countries that
under report are large emerging economies (china, India, Brazil, Russia) which
could finance these efforts but for some reason do not.

Julia Koricheva. Tree species richness and genetic diversity
on leaf miners. What is the relative importance of these two effects. Two
experiments, one manipulating tree richness -up to five species, and another
with up to eight clones of silver birch. Silver birch was in both experiments,
so was the focus of leaf miner surveys. Tree richness affects miner richness,
but not abundance. More leaf miner species with higher tree richness in first
year, but not second. For genetic diversity, miner richness also increased with
number of clones. Looked at effect sizes of two experiments and genetic
diversity appeared to have a stronger effect on leaf miner richness.

Tommaso Jucker. Complementarity in functional groups
enhances wood production. He noticed that there were eighty talks on BEF at
INTECOL. Four species combinations two pines and two oaks. Biomass increased
with richness, but looked at more detail, growth over the past ten years from
wood cores. Both pines grew much better in mixture, but oaks only increase
growth when other oak is present. Tree that benefit the most are small trees.
For pines, wet year showed largest increase in growth, most room for
complementarity.

Siobhan Vye. Responses to multiple stressor change. Examined
stressors in coastal systems. Looked at how an invasive species affected
community response to stress by experimentally combining species in mesocosms
and manipulated nutrient enrichment and temperature. Invader increases
productivity. The presence of the invader determined how the stressor
influenced community functions.

Sebastian Meyer. BEF changes over time. A number of studies
show that BEF experiments increase in strength over time. Examined how
functions change over time using Jena experiment. How many different functions
show changes over time? Over half of functions are influenced by diversity
generally. He regressed the richness-function slopes across time, and about one
third of functions showed increasing diversity effects over time. What are the
mehanisms? The stronger relationships are driven by a combination of changes in
high diversity treatments and changes in low diversity treatments.

Thursday, August 15, 2013

The thing about peer review is that there isn't much of an education process. Maybe you've published a paper or two and experienced the process as an author, and then you're asked to start reviewing for other authors. It's a bit like the telephone game - you mimic the reviews you received, maybe noting what you liked and avoiding what you didn't like. But that's often all you have to go on, and when you're just beginning a little advice might come in handy. To that end, the British Ecological Society has just published a pretty useful Peer Review 101 text. This should be required reading for new reviewers.

Monday, August 12, 2013

The annual ESA meeting functions in a lot of different ways. There are the obvious: the sharing of ideas and work, the discovery of new ideas, methods or sources of inspiration, networking and job finding, social reunions. But it also functions as a kind of report on the state of the field (and that's not even considering sessions meant to explicitly do this, like the panel “Conversations on the Future of Ecology”). The topics and methods presented say a lot about what ideas and methods are timeless, what is trendy, and over many meetings, where ecology appears to be going. If you go to enough ESAs, you are participating in a longitudinal study of ecology (or at least your subfield).

I went to my first ESA five years ago in Albuquerque, NM. One of the things that struck me was that there were two Community Assembly and Neutral Theory sessions and many talks in those focused on tests of neutral theory, particularly looking at species abundance distributions (SADs) and various iterations of neutral models. There are usually still one to two sessions called Community Assembly and Neutral Theory, but five years later, I don't think I saw a single talk that looked at SADs for evidence of neutral theory (and only one or two talks that were named to explicitly include neutral theory). Instead, the concept first introduced by Hubbell has morphed from "neutral theory" in to something slightly more general, designated "neutral dynamics". This gets used in a lot of ways – most precisely, neutral dynamics are in the spirit of neutral theory, suggesting that population demographic rates are similar, allowing long-term co-occurrence. Sometimes this is cited with reference to equalizing fitness effects in a Chessonian framework, where similarity in fitnesses prevents exclusion despite overlap in species niches. But it also seemed to get used in a default sort of way, as the explanation for why niche differences between species weren't discovered by a study, or else "neutral" was used interchangeably with "stochastic". In any case, the pattern appeared to be a move from highly specialized and precisely defined usage of the term, to broader incorporation of the concept that had suddenly acquired several, often less precisely defined meanings. Instead of being the central focus of a few specialized talks, neutrality was commonly invoked as a minor theme or explanation in many more talks. It is not what I expected, but its continuing usage suggests that neutrality has developed a life of its own.

Other topics similarly seem to have taken on separate lives from their initial application; even over the short time I've been attending ESA. For example, sessions focused on simple applications of ecophylogenetics methods (overdispersion, clustering, using different systems) were relatively common 3-4 years ago, while there wasn't a single contributed session specifically named for phylogenetics this year. There was however many sessions in which phylogenetic work formed the backbone of talks that were about broader questions, including in the "Evolution, Biodiversity, and Ecosystem Function" session and the “Coexistence of Closest Relatives: Synthesis of Ecological and Evolutionary Perspectives”. In the best case scenarios, it seems like even over-hyped approaches may be used with more nuance in time, as people recognize what information these methods can and cannot provide.

Sometimes it did seem that there is a lag between when critiques of certain methods or ideas are expressed and when they actually get incorporated into research. I could be wrong, but it seems this is most common where the research is focused on particular study systems or species, and methodology may be driven more by precedent in the literature and criticisms may take longer to infiltrate (since they aren’t the main focus of the work anyways). And unfortunately, the topics and sessions which appear to be timeless are those on human-related applications (restoration, climate change, invasion). Those pressures are sadly unchanging.

*The great thing to do would be map out changes in keyword frequency over the ESAs that have archived programs. Unfortunately, I don’t have the time/motivation.

Thursday, August 8, 2013

The talks I saw today were uniformly good and a number were excellent. At least half of them focused on the many implications for ecology of nature's innate variability. It appears that community ecologists have decided that now is the time to start considering the fact that the environment is not stationary, which was long a default assumption in most theoretical and empirical work. Many of the talks I saw reflected this changing approach. The other half were part of a symposium organized by Sharon Strauss that looked at coexistence among sister species. This topic, combining as it did large-scale evolutionary and biogeographic processes with local competitive interactions made for a broad range of talks and some interesting attempts to reconcile different methodologies and scales.

Our variable world

Many of the past studies on environmental variability and coexistence involve desert winter annuals. Desert winter annuals are limited by available water, and the yearly rains vary greatly in the amount and timing of onset. The hypothesis is that variable germination (via prolonged dormancy in seedbanks) may allow desert winter annuals to reduce the variance in their fitness between years. Alejandra Martinez-Berdeja presented some tidy hypothesis testing using biogeographical gradients: if variable germination is an adaptive response to variable precipitation, she hypothesized that differences in germination variability might be expected where precipitation is more or less predictable. Looking at the three North American deserts, she predicted that variable germination would be greater where rainfall was more variable (bi-seasonal) compared to winter rainfall deserts. She measured the involucres (dispersal structures determining seed release) on collected seeds and found that indeed they were larger in more variable rainfall deserts, producing greater variability in seed release. Further, in winter rainfall deserts, variability in the size of involucres was correlated with variability in rainfall at a site, again suggesting a link between germination variability and rainfall variability. Her next step will hopefully be to expand the tests look at the effect of autocorrelation in rainfall likelihood on bet-hedging, since this should increase selection for bet-hedging type adaptations.

David Vasseur gave a great talk showing how extreme environmental conditions--which we are seeing as part of the changes in mean and variance of the climate--could have particularly detrimental effects on population growth rates. Species have temperature performance curves that reflect the relationship between their fitness and the temperatures they experience. Vasseur showed that in the tropics, species tend to have much narrower temperature ranges over which they can grow and survive than species in the temperature regions, and experts agree that these narrower curves give tropical species less ability to deal with increasing temperatures. But variability is rarely considered in this equation. When variability is present, long-term species fitnesses will be subject to Jensen's inequality (nonlinear averaging) mean that shape of these performance curves is additionally important: that in some situations (concave curves) variability is particularly detrimental, and in some situations (convex curves) it may have a beneficial effect. Vasseur then used models to show that as temperature variation increases, it is increasingly likely that its effect will be negative, and high variation will produce high extinction rates. In fact, on average Vasseur predicted that temperature variation would have negative effects, a concerning conclusion.

Sisters getting along

This organized symposium was advertised as: “Whether closest relatives coexist reflects the often opposing effects of limiting similarity, mode of speciation, reproductive isolation, niche conservatism, competition and facilitation, which may be strongest in sister taxa; using new phylogenies, niche models, and experimental approaches, we explore coexistence in closest relatives in both plants and animals.” It was an interesting and useful idea – sister species (species who are each other’s most recent relative) are an important tool to understand how evolution, biogeography, and ecological interactions determine coexistence. The content of the symposium provided a number of example systems, methods, and approaches that suggested this was an important but still far from cohesive area of work. Mark McPeek spoke about the damselfly work he has done over the last many years, which shows that sister species are sympatric and ecologically identical, co-occurring happily through neutral dynamics. In contrast, Richard Glor talked about his work with Hispaniola anoles, where biogeography is an explanation for radiations, close relatives use different microhabitats and rarely compete locally and traits are divergent among close relatives. Looking at California plant species, Brian Anacker’s talk suggested something in between these extremes. A broad survey showed that 80% of sister pairs were sympatric, range overlap was modest but not uncommon, but asymmetry in range size was high. Ecological differences between sister species were not particularly clear in the handful of traits he examined, not even for reproductive traits. Sister species can and do co-occur, although not in large portions of their ranges. Having established the current state of knowledge, hopefully the symposium will stimulate greater focus on the construct of sister species as a way of understanding coexistence at multiple scales.

Finally, not being willing to miss another talk with the word “derby” in the title, I attended Daniel Atwater’s talk, “Is competition among plants like a boxing match or a demolition derby? Why competitor suppression may not matter in plant communities”. Atwater argued that there were two ways to win at plant competition – be good at suppressing your competitors, or be good at tolerating them. When in competition with a single individual, being a strong suppressor should be favoured, but in competition with multiple species, tolerance may be a better strategy. That’s because resources spent on suppressing one competitor may also benefit any other species involved in the competition. In such cases, tolerance of your competitors may provide the greatest benefit. (Apparently this scenario is like a successful (but frowned upon) strategy (sandbagging) in a demolition derby). Atwater used experimental data from blue bunch grass grown in competition with spotted knapweed to parameterize a model in which he found the optimum strategy in single versus multi-species competitions. The model agreed with his hypothesis that tolerating competitors is favoured when multiple species are competing. Although I am not clear on whether competitive strategies are easily classified as tolerant vs suppressing it was an interesting talk, and left me thinking about new questions.

Wednesday, August 7, 2013

All the best quotes that I caught today were undeniably from Ben Bolker, who also gave an interesting talk.

"The hallmark of great theoretical ecology is that it is obvious in hindsight. When you explain it to someone, they say well, of course."

In relation to a philosophical issue: "That's a beer question, not a coffee question".

To explain the reason he and his coauthors chose to build a model to explore the question, Bolker showed a Dilbert cartoon illustrating the truism "When all you have is a hammer, everything looks like a nail".

Only one full day left to go, and it looks like it will be a good one!

Sometimes there are moments in my career where feel truly
fortunate. Today I was fortunate enough to be a speaker in a session on
evolution, biodiversity and ecosystem function. The other talks in this session
were outstanding, full of amazing insights into how historical evolutionary
dynamics affect modern-day ecological patterns. The presentations were followed
by a fantastic panel discussion stimulated by thoughtful questions from the
audience. The talks covered a range of topics from including species interactions
in models of evolutionary change to using traits to understand coexistence to
trying to find patterns when close relatives do not coexist.

The first talk from Luke Harmon on finding phylogenetic
signatures on species interactions was incredible. He is an entertaining
speaker and included references to his kids finding leaf cutter ants.He show us how one could fit
phylogenetic models that include coevolution. The negative effects of
coevolution should affect trait evolution and one should see this signature in
variance-covariance matrices. Random evolutionary change generates covariance
between species. Stabilizing selection will remove this covariance, while with
competition there should be negative covariances apparent. From models we see an
interesting signature where older species are able to diverge and fill niche
space (thus diverging rapidly) while later species are constrained in their
evolution (thus remaining similar). Older species can contribute more to
ecosystem function because of historical competitive effects.

Next was Nathan Kraft talking about how traits can potential
shed light on fitness and niche differences in coexisting species. In a plant
experiment with focal species grown alone and at different densities with
competitors, he showed that very few pairs met the conditions for coexistence.
For those that do appear to be able to coexist, no traits were associated with
fitness difference, but several traits appeared to be associated with fitness
differences. Multivariate analysesshowed that an assortment of five traits collectively appeared to be
associated with niche differences. Some of these traits appeared to also
explain fitness differences, revealing the complexity in assigning traits to
specific ecological effects.

In Jeannine Cavender-Bares’ talk, she examined how
evolutionary transitions in seed dormancy helped explain modern day ecological
patterns in the Fabaceae family (the pea and bean family). The Fabaceae
includes species that have dormant and non-dormantseeds. Dormancy should be favored in certain environments
(e.g., less predictable and poor environments). Large seeds are much less
likely to be dormant, as well as those occurring at lower latitudes. Historical
transitions in dormancy seemed to be correlated with changes in temperature
lineages experienced.

Finally, Sharon Strauss critically examine dhow to separate
history form ecology. We need to be cognizant of scale effects, where larger
scale observations will include more close relatives than we usually see at
local scales. Communities contain ‘ghosts’ of past competition and assembly. If
species originate allopatrically (in separate places), then we expect that close
relatives should not coexist, which can skew our inference about how ecological
differences have evolved. Within habitats we seldom see closely related species
coexisting . She gave a number of great Californian examples of species
appearing to co-occur at large scales but not locally. For example, Limnanthes
plants occur in the same region but species never co-occur in the same vernal
pool.

These talks represent the collective excitement about the
fact that we are entering a new synthesis in ecology. Evolution is required to
understand ecological patters and ecological interactions are need for
understanding evolutionary change. These talks exhibited where the forefront of
this synthesis is, and it was a great afternoon of talks.

Day two started off on a high note with Bernhard Schmid's talk on evolution in biodiversity-ecosystem function (BEF) experiments. He is one of the originators of the Jena biodiveristy experiment, for years they have been maintaining plant species in monocultures and in polycultures to assess how much more ecosystem function is produced by multi-species assemblages over single species monocultures. However, it occurred to Schmid that species in these two contexts face different pressures, which may have resulted in evolutionary changes. In monocultures, species face high intraspecific densities and thus competition is severe, as is negative indirect effects like pathogen sharing and herbivory rates. Within polycultures, intrraspecific interactions may involve niche differences, with opportunities for character divergence to further stabilize coexistence. He reported on an experiment that took seeds and cuttings from monoculture and polyculture populations and grew then in monoculture or polyculture. He showed that individuals originating from monoculture did better in monoculture and species originating from polyculture did better in polyculture. The implications are fascinating. If the rate of evolutionary change in performance are equivalent between monocultures and polycultures, the BEF relationships should remain constant. However, if the rates of change are greater for polyculture populations the BEF relationship should get stronger over time. Conversely, BEF relationships should became weaker if higher evolutionary change in monoculture.

It was hard to top this talk, but there were several other impressive talks as well. Jacob Vander Laan used a country-wide dataset on aquatic insect diversity across the USA and showed that at larger scales, beta-diversity decreases with connectivity, but is seemingly unaffected by environmental heterogeneity.

Restoration is community assembly with management goals and Emily Grman gave an interesting talk on assessing the success of prairie restoration by accounting for management activities, landscape, historical and local abiotic factors. She showed that management activities were the most important, with species-rich sowings result in rich communities, even though many of the species are not those in the sown mixture. Sowing a high diversity of grasses did not increase diversity, but high diversity of forbes did. Other factors like landscape influences and local factors were not important.

Will Pearse examined plant diversity patterns and homogenization across six large urban centres. He showed that there has been little taxonomic homogenization, but substantial phylogenetic and moderate functional trait homogenization. Beyond the interesting questions about how urban centres may cause biotic homogenization is the new tools that Pearse created for these analyses, and that are available online. As a self described 'shampoo salesman', he created a general tool called Phylogenerator that creates a pipeline that makes estimating trees form sequence data more efficient -definitely a tool that ecologists should be using. He further created a way to quantify complex leaf shapes and has a tool available for that, called Stalkless.

All in all , this was a good day, one that has stimulated new questions and approaches. These talks got me thinking about some of my data and experiments and how I can extend them to new questions.

Monday, August 5, 2013

With day 1 over, ESA 2013 was off to an excellent start. Minneapolis seems like a very friendly place, and I enjoyed perhaps the most chatty bus ride I've ever experienced. As always, I failed to determine the best point on the trade off plot between cherry-picking certain talks based on topic, speaker and friends, and staying put in a session with an interesting topic. Nonetheless I managed to see some really good talks.

Among them, I saw Lauren Shoemaker in the Theoretical Ecology section, who illustrated how to model the four metacommunity paradigms (I.e. species sorting, mass effects, neutral, and patch dynamics) with the Chessonian framework of equalizing and stabilizing forces. She illustrated how both deterministic and stochastic models could replicate dynamics from the four paradigms. This suggests that rather than the usual description of the neutral paradigm as stochastic and the mass effect and species sorting paradigms as niche-based and therefore deterministic, the terms niche and deterministic and neutral and stochastic should not be synonymous. Rather, in the Chessonian framework, fitness differences drive neutral-type dynamics and spatial niches structure the species sorting and mass effects paradigms. More importantly, the results show how the paradigms are just a few sets of points on the much broader set of parameter values that could describe metacommunity dynamics.

It must be funny for Peter Chesson to follow up a talk in which his name is used as an adjective. After the talk on the Chessonian framework, he spoke about the fact that environment is fluid and non-stationary, yet models of communities have almost always treated it as being at equilibrium. Since it is not, ideally models of community dynamics would begin to incorporate environmental variation, and ask questions more relevant to non-equilibrium systems. For example: when is long-term persistence expected, given this non-stationarity and can communities in a non-stationary system still be stable? He showed that including environmental fluidity into models doesn't mean that communities are necessarily unstable, for example, when spatial and temporal trends of environmental variation match, communities may be stationary.

In another of many good talks about temporal variation (seemingly a popular topic of late), Colin Kremer showed that altering the basic characteristics of abiotic temporal variation (amplitude, means, periodicity) changed the amount of diversity present as communities evolved over time. Temporal variation isn't a simple concept anymore than spatial variability is - it has different characteristics with different effects on ecological dynamics and needs to be considered in greater depth.

My biggest disappointment was that I had a time conflict and couldn't attend a talk titled "Significant changes in the skin microbiome mediated by the sport of roller derby". No doubt I would have learned a lot.